Just like Sherry can't be called Sherry or Scotch can't be called Scotch unless they meet certain geographic, constituent, and/or process requirements, Bourbon has these (Congress 1964): 1. Mash bill must be at least 51% corn. The rest is often wheat ("wheated bourbon", the lightest and sweetest), rye, barley. 2. Cannot be distilled past 160 proof. Must enter barrels at <=125 proof (thus you get a standard "cask strength" maximum ~60-65% abv, some really great stuff in this category. It is possible to go up a bit in proof in the barrels. Usually diluted to 80+ proof. 3. Aged in new charred oak barrels. This creates a constant need for new barrels by distillers, and a secondary market for other spirits to age in (bourbon barrel beer, bourbon barrel wine, etc.) - flavors and alcohol seep back out of the barrel. 4. All the above must be done within the United States. Age Statements: 1. If aged a minimum of 2 years, it can be called Straight Bourbon (not required to be labeled thusly). 2. If aged less than 2 years, age statement must be on bottle. 3. Age statement must be that of the youngest constituent bourbon (some distillers blend a variety of ages; most blend a variety of barrels from different locations in their rickhouse - different characters). Bonus: "Bottled in Bond" / "Bonded" Whiskeys (not just Bourbons): 1. Distilled entirely by 1 distiller at 1 location in the United States (i.e., the label meant something). 2. Aged a minimum of 4 years at a facility under federal supervision(!) (not doctored with iodine, colorants, turpentine). 3. Entered bottle at >=100 proof (not watered down).